Force responsive switch



March 24, 1970 H McRo'sKEY FORCE RESPONSIVE 'swITc'H Filed Feb'. s, 1969 r .f www@ f 0 @www V7 ww W Mmwrv 6 Hrl H v/ d linnn w A A JIHJT m MM ft w 4 Mw G p U.S. Cl. 200-61.49

3,502,832 FORCE RESPONSIVE SWITCH Leonard H. McRoskey, 420 Loring Ave., Los Angeles, Calif. 90024 Filed Feb. 3, 1969, Ser. No. 796,042

Int. Cl. H01h 35/02, 35/14 Claims ABSTRACT oF THE DISCLOSURE BACKGROUND OF THE INVENTION The present invention relates to a force responsive switch which makes and breaks an electric circuit in response to various forces such as gravity, inertia, centrifugal or vibration producing forces.

In the prior art, it is noted that United States Letters Patent No. 2,996,586 discloses a magnetic switch having a body of the order of one inch in length in which a rod between a pair of magnets is supported by the magnets in spaced relation to angular contact members adjacent to the ends ofthe rods.

Also in a copending application in which this inventor is one of the coinventors there is a disclosed switch which is designed for the particular use referred to herein. This application is identied as the application of James A. Carley, Leonard H. McRoskey, and Robert Q. Parsons, Ser. No. 679,098 filed Oct. 30, 1967. Switches of this prior invention have proved highly satisfactory in the service. Their functioning has been superior to all other prior art known to applicant or to applicants customers. In the manufacture of these glass enclosures of the tumbler switch of the prior invention they are basically a hand operation and production is necessarily at a relatively slow rate.

In manufacture, heating glass to the melting point in order to form a homogeneous bond often results in a rejected part. This is caused by the soft plastic state of the glass which often upsets the critical tolerances of the contact elements. Difliculty is experienced in fixturing various elements of the switch to produce absolute uniformity in the switch unit thereby necessitating an individual test of each switch to determine its operating parameters. 'Also the application of heat upon the glass enclosure to effect a bond between the base bead and the glass tube at times distortsl the terminals and oxidizes the plating on the terminals.

SUMMARY 0F THE INVENHON In the force responsive switch. of my present invention al1 of the manufacturing diiculties experienced with the invention disclosed in theapplication referred to above have been eliminated with the result that there is uni- 3,502,832 Patented Mar. 24, 1970 formity in production which reduces rejects to a very minimum and there is also economy in the manufacture and assembly of the parts. vBy reason of the details of the present invention precise positioning of the contact terminals within the base is difficult, the leads being molded into position when the base is cast. There is precise fixturing of parts during the manufacturing process thereby eliminating the requirement to run every unit through an exhaustive test series. Elimination of heat to bond the base to the enclosure results in elimination of the difficulties where a glass enclosure must be heated to a high temperature. Automatic production is permissible because the base and envelope are precisely of the same configuration and tolerance and are fitted together exactly the sa-me each time an assembly is made. Fixturing of all elements in assembly a-ssures uniformity of subassemblies and uniformity in the nished switch. The production rate is increased greatly by the use of an envelope and base which may be secured together without the application of heat. Furthermore, use of different materials in the center pendulous contact is permitted because no distortion will occur because of heat concentration resulting from the sealing and bonding of a base such as glass.

BRIEF DESCRIPTION OF THE DRAWINGS Referring to the accompanying drawings which are for illustrative purposes only:

FIG. l is an enlarged longitudinal sectional view of a switch made in accordance with the present invention;

FIG. 2 is a cross-sectional view taken along the line 2-2 of FIG. 1;

FIG. 3 is a sectional view taken along the line 3 3 of FIG. l; and

FIG. 4 is an elevational view showing the manner in which the base and-electrodes are assembled together as a unit prior to the adding of the pendulous contact and prior to the assembly of the base with the envelope.

DESCRIPTION OF THE PREFERRED EMBODIMENT In the drawing the numeral 10 indicates the base which is formed from a dielectric material such as a polycarbonate resin. It is cast by a standard method. The base 10 has a cylindrical projection 11 which in the form of the invention illustrated is .125 inch in diameter and is chamfered at .the top as indicated at 12. The base 11 has a llange 14 which provides a flat upper surface 15.

I The numeral 17 is a dielectric envelope which may be made from polycarbonate resin or its equivalent, this envelope having a cylindrical portion 18 whichfin the form shown is .750 inch long and has an inner diameter of .125 inch. One end of the-envelope 17 is closed by an integral rounded end 19 and the other end is left open and is provided with a flat end face 270. The envelope andbase are assembled together so that the inner cylindrical surface21 of the envelope fits on the cylindrical projection 11 and the end face 20 of the envelope engages the face 15 of the base. These two parts are secured together by a suitable glue such, for example, as a polycarbonate solvent. The connection between these air parts is gas tight and enables the chamber 25 of the envelope to be evacuated and filled with an inert gas such as argon.

3 When` the base is molded electrodes 30 and 31 are molded in place, being accurately positioned by suitable iixturing and the joining of the base material and electrodes is gas tight. These electrodes are made from a suitable material such as Dumet which is an alloy consisting of 54% iron, 46% nickel, and copper plated. Electrode 30 is .016 inch in diameter and extends through the base on an axis which is parallel to the central axis of the base cap. The electrode 30 is positioned so that its radially outermost portion as indicated at 32 is on a diameter of .125 inch so that it will contact the inner wall 21 of the envelope 17 throughout its entire length. The extending end of the electrode 30 within the envelope 17 is formed into a ring as indicated at 30, this ring having an outer diameter which is the same diameter as the inner cylindrical surface 21 of the envelope. In this way the portion of the electrode within the chamber 25 and the ring contact 33 are supported yby the inner wall 21 of the envelope 17. The portion of the electrode which extends downwardly from the base 10 is of suitable length so that an electric circuit wire may be connected thereto. This is also true of the electrode 31. v

The central electrode 31 is placed on the longitudinal axis of the envelope and the base and extends into the chamber 25 a sufiicient distance so that a pendulous contact may be attached thereto.

There is a flexible pendulous contact 40 which when the axis of the switch is vertical extends concentric to the longitudinal axis of the envelope and base. This movable contact is in the form of a tightly wound helix or coiled spring and is made from a suitable conductive material such as tungsten wire. The diameter of the wire used is approximately .003 inch and the diameter of the helix of the spring is approximately .016 inch. The dimensions given here are those which are used where the switch is intended to respond to forces of two Gs gravity in order to close the switch or, in other words, to cause the pendulous contact 40 to move into engagement with some portion of the ring contact 33. For clarity the drawing of this application shows the coils of wire spaced apart although they are, in fact, closely wound as previously explained. It will be noted that the movable contact 40 is sufficiently long so that the upper portion projects through the ring contact 33. As thus arranged the coil spring forms in effect a pendulous contact although it does not carry a weight at its free end.

By utilizing this construction, the coils of the spring provide throughout the length of the spring contact surfaces which are engageable with the ring contact 33 irrespective of the position of the ring contact along the length of the movable contact.

The helical spring is reduced in diameter at its lower end as indicated at 42, this diameter being such that it will slide over the inner end of the electrode 31 so that the movable contact 40 Will be Supported in an accurate concentric position. The lower end 41 is secured to the electrode 31 by bonding at a point such as indicated at 42 which is spaced away from the larger diameter of the Ahelix in order that the heat of the bonding operation which is a spot welding operation will not reach the pendulous portion of the movable contact and distort or draw its temper.

The amount of force required to close the contacts may be varied in a number of ways. For example, if the envelope 17 is of larger diameter so that the ring contact 33 may be made of larger diameter, the force required will be increased. Also the amount of closing force required is dependent upon the diameter of the helix of the pendulous contact 40. It will also be apparent that since the contact 40 is supported in the manner 0f a cantilever structure the amount of deflection required to effect closure of the contact will vary depending upon the position of the ring contact 33. In other words, it may be placed lower or higher in the envelope 17. Also the force required to close the contact will depend upon whether the switch is vertically positioned as shown in thedrawings or horizontally positioned -with the axis of the envelope and base and related parts in a horizontal position; in such event, gravity will cause the pendulous contact 40 to bend downward bringing it closer to the ring contact 33 on the lower side and this, of course, will cause the contacts to enga-ge at a lower force.

In the manufacture of the switch of my invention, the envelopes 17 are all made of a standard size; they are identical to each other for a given switch. Also the base 20 is identical in size so that each base will accurately tit the envelope. An additional important feature is that the electrodes 30 and 31 are heldin a xture and are passed through the molds in which the ybase 10 is molded so that these parts will be absolutely accurately positioned in the subassembly such as shown in FIG. 4.

After forming the envelope and base with the electrode in place, the next operation is to secure the pendulous electrode 40 in place and this is done as previously described. The next operation is to slide the envelope and the base together so that the parts will rest in a partly assembled position with the base slightly spaced from vthe lower end of the envelope. The parts are then placed in a vacuum chamber, the air evacuated, and the chamber is then iilled with gas so that the chamber 25 of the trembler switch will also be filled with an inert gas such as argon. The parts are then completely assembled and the sealing operation is performed by using, for example, the polycarbonate solvent as previously referred to. The plastic parts may be coated, or plated with a non-porous material, should they be porous and permit leakage through the walls.

In operation the switch may be positioned vertically or horizontally or in some intermediate position. The electrodes 30 and 31 are connected in the electrical circuit which is used to perform the desired function, such, for example, as exploding a land mine. It will be understood, of course, that this trembler switch may be used anywhere that it is desired to close an electrical circuit in response to a vibratory force.

I claim:

1. A force responsive switch, comprising:

(a) a dielectric base;

(b) a dielectric envelope mounted on said base and fitted over a portion thereof and providing a sealed chamber;

(c) a pair of electrode terminals fxedly supported in said base; one of said electrodes extending along the inner wall of said envelope and having a ring contact in spaced relation to said base; and

(d) a resilient elongated pendulous contact supported against movement at one end on the other of said electrodes with a portion positioned within said ring and extending therethrough and including means whereby said contact engages said ring contact upon predetermined deflection thereof.

2. A switch according to claim 1, wherein the pendulous contact has a uniform configuration transversely, and when the switch is vertically positioned will have'its longitudinal axis centered within said ring, and upon the switch being horizontally positioned will have its axis more closely spaced to one side of said ring.

3. A switch as defined in claim 1 in which said envelope has a cylindrical portion and in which said ring Contact is annular and is in engagement with said cylindrical portion of saidenvelope.

4. A switch as defined in claim 1 in which said pendulous contact is a helically wound wire with the helix closely wound, the wire being of a diameter of the order of .003 inch.

5. A switch comprising: v

(a) a dielectric base'having acylindrical portion;

(b) a cylindrical dielectric envelope closed atV one end and having its other end closed bythe cylindrical portion of said base extending into said envelope;

(c) a pair of electrodes cast in said base and extending axially therethrough, one of said electrodes being positioned to extend axially in contact with the inner surface of said envelope and the other of said electrodes being positioned on the central longitudinal axis of said envelope;

(d) a ring contact formed on the end of said first mentioned electrode, said ring contact being in engagement with and supported by the inner cylindrical wall of said envelope; and

(e) a coil spring of resilient current conducting material, said spring consisting of closely Wound helix, said pendulous Contact extending through said ring contact, and including means whereby said pendulous contact engages said ring contact when subjected to a force adequate to cause said pendulous contact to cantilever into engagement with said ring contact.

References Cited UNITED STATES PATENTS ROBERT K. SCHAEFER, Primary Examiner M. GINSBURG, Assistant Examiner 

